Well, a Google search for "bitextual" turns up several different types of entries, but what I mean by this word is an author who writes in more than one genre. I first heard it used this way by Chris Abani (poet and novelist). I don't know if he coined the phrase, but I think it's a great word and encourage writers to both use it, so that it will become more widely known, and practice it, because we can all benefit from literary cross-training.
Thinking about this made me wonder how many other writers I admire are bitextual. This is the short list I came up with so far:
Margaret Atwood, famous for her novels, also wrote many well done poems that are polished and mythic.
Vikram Seth, author of the epic A Suitable Boy, wrote a novel in verse that I recently picked up at a used book store (but I can't recall the title at the moment).
Jan Clausen, one of my advisors at Goddard, has written extensively in both poetry and fiction, and talked to me about how switching back and forth can feel freeing.
Maya Angelou, of course, has written a library of memoir and also several volumes of poetry.
I'm sure there are others who have been masters of more than one form... feel free to add to this list! Let's get bitextual...